Hot Legs in Heart Failure: Examining Changes in Core Temperature and Lower Limb Blood Flow in lower limb immersion therapy

The study intervention will involve 45 minutes of lower limb immersion in either thermoneutral (30°C) or hot water (40°C) bath. We will be using a water tank (container) that will connected with ICool System that will maintain the set temperature throughout 45 mins of immersion. Participants will immerse their both legs in water tank which will be filled up to either knee or ankle height (randomly assigned). During the intervention participants will be seated on the chair with their both legs immersed in the water. We have set up the lab with a wall mounted TV screen (at eye level) that participants can watch during 45 minutes of water immersion. Our research team comprises researchers with experience in undertaking hot water immersion interventions, additionally all the interventions will be supervised by a physiotherapist. The water temperature will set to desired level prior to the immersion. We will be using an ICool system that circulates the water between the system and the container to maintain the desired temperature throughout the set period. Water temperature will be monitored throughout the experiment through the digital monitor on the ICool System. As detailed previously, we have undertaken a similar pilot study in establishing this protocol and our team includes physiotherapist, exercise physiologist and clinical physiologists will expertise in undertaking similar interventions in individuals cardiorespiratory conditions. The study will involve 5 experimental visits - a familiarisation visit and 4 experimental visits with a week interval between the visits to allow washout. Visit 1 (familiarisation visit): This visit will involve obtaining the informed written consent and familiarising the participants to the research protocol. Participants will be detailed about all the intervention involved before getting the consent signed. After obtaining the informed written consent, we will obtain the anthropometric measurements and set the height of the table ensuring the comfortable posture while legs are immersed in the water tank. We will also measure the baseline Vascular function and skeletal muscle tissue oxygenation. Visits 2 to 5: during these 4 weekly sessions participants will undertake four 45 mins hot water interventions in random order. The interventions are: (1) Angle height thermoneutral (30 degree C), (2) Ankle height hot (40 degree C), (3) Knee height thermoneutral (30 degree C) and (4) Knee height hot (40 degree C). Each intervention will take 45 mins. Thermal response will be monitored during the intervention and on the completion of each intervention vascular function and skeletal muscle tissue oxygenation will be measured.